The terms of instrument specification and instrument data sheet are used interchangeably by some practitioner. Both are referred as the documents or information sheet which specifying the details of instrument. You often see manufacturers use the word “specification” in their product flyer and some time you get “data sheet” in different manufacturer product sheet.
For those who involve in the project, instrument specification and instrument data sheet are two different documents. Instrument specification is a document which limit the boundary of instrument. It says the general rule of how to specify an instrument to be used. Meanwhile, information in data sheet is much more detail and much more specific to suit the application.
The following example provides how the specification and data sheet talk about instrument range:
Specification: “The range of instrument must be selected so that maximum value of process variable does not exceed 90% of calibrated range”
Data Sheet: “0 – 100 barg” (in which case the maximum process pressure is 90 barg)
Instrument specification is to be generated first and based on this document we can derived the data sheet while getting other information from others documents during preparation of instrument datasheet.